DE2257304A1 - POLYAETHYLENE WITH IMPROVED RESISTANCE TO TENSION AND IMPACT - Google Patents

Description

Polyethylene with improved resistance p ^ e ^ en
Tensile and impact stress;

The invention relates to a polyethylene with improved strength against Rissbüdung under tensile and impact stress, that by Compounding the polymer obtained with special additives as well as processed articles obtained from polyethylene to which additives have been added.

It is known that polyethylene containers are often used to hold polar liquids, surfactants,
Include mineral oils, etc., which lead to the formation of cracks in the polymer.

This tendency of polyethylene to crack is commonly referred to as "Envirenmetal Stress Cracking" and according to the
Methods ASTM D-1696 and ASTM D-2552 measured. It is referred to below as ESCR.

In addition, it is very important that the container is made of polyethylene
are resistant to possible impacts or blows that can occur during use (e.g. when falling). These

309825/1006

Resistance is measured in accordance with ASTM D-256 and classified as Notched impact strength IZOD.

According to the present invention, the ESCR and impact resistance IZOD of polyethylene is improved by compounding the polymer with low percentages of an additive selected from the compounds of the following general formula

R -Γ- R ¹ O (R ² O) _n -j- X

where R is a hydrocarbon chain consisting of an alkyl, Can consist of alkenyl or cycloalkyl; (R 0) a poly

2
is ether chain, in which R is an alkyl radical which can be unsubstituted or substituted by alkylene, arylene, cycloalkylene, aralkylene groups and η is a number from 1 to 100

1
represents; R can be a radical selected from those for R

radicals indicated, in this case R and R form a single hydrocarbon group with a number of carbon atoms in the range of 5 to 30; or where R can be an aryl radical, again the sum of the carbon atoms of R and R being from 5 to 30; where R can also be selected from the radicals,

ρ
those given for R, in which case the polyether chain is extended on one unit; wherein X is a group selected from -CHpCOCH, -CHpCHO, -CHpCN, -CH ₂ COOMe, -CH ₂ OH, -CHpCOOR, wherein Me represents any monovalent metal and R ° is a hydrocarbon:
is listed residues

R ° is a hydrocarbon radical from the group of the above

According to the present invention, any polyethylene can be improved in the above properties; however, a particular advantage is achieved when the invention Applied to polyethylene used in the manufacture of containers (containers) or generally industrially manufactured Articles used, which is usually a high density polyethylene with an index in the range 3.1-10 is.

309825/1006

The ESCR problem of high-density polyethylene is generally produced by copolymerization of ethylene with a low percentages ^- s higher dissolved £ K-olefin. The copolymer obtained has a higher ESCR strength, but has a mechanical stiffness which is below that of the homopolymers.

In contrast, when using the method according to the invention, a product is obtained whose ESCR resistance corresponds to of the copolymers and the stiffness of which is substantially the same as that of the homopolymer.

Another advantage of the products obtained is the impact notched strength IZOD, which is higher than that of the copolymers. and Homopolymers with the same melt index (MFI) lies.

The percentage of additive used is between 0.1 and 6 based on the weight of the polymer.

The compounding of the above 'mentioned additives is carried out according to conventional methods, using conventional equipment (mixing rolls, Banbury vertical extruder, etc.).

The following examples serve to illustrate the invention, without restricting them.

example 1

One high density polyethylene (0.9577 g / cnr) and one MFI of 0.27 g / 10 minutes was given with different percentages

of a product of the following formula

- Ό - (CH ₂ - CH ₂ - O) ₁₀ - CH ₂ - COONa

mixed.

The results of the mechanical tests carried out are shown in table Λ .

3 0 25/1006

Table I.

Weight # additive ESCR ^k '.'^; Hardness in the composition

Notched impact toughness IZOD kg cm / cm

Obtain- ing- ^ ^J Bruchtene stocks. elongation strength tensile stress _Q , (kg / cm kg / cm * °

O UD OO

0.5

40

63

88

112

137

10,600

12,000

(1) ASTM D 1696

(2) ASTM D.

(3) ASTM D.

(4) ASTM D.

28

281

278

930

278

284

860

Example 2

The polyethylene of Example 1 was made at various percentages of a product of the following formula

-O- (GH ₂ - CH ₂ - O) ₈ - CH ₂ - CH ₂ -OH

mixed.

The results of the mechanical tests carried out are shown in Table II.

309825/1006

Table II

% By weight of additive ESCH in the composition the)

Hardness kg / approx

Impact notch- obtained tensile- fracture toughness strength. strain
IZOD kg cm / cm kg / cni ¹ "tensile stress%

kg / cm ^

'J 4 y 0.5 1 60 2 87 3 120 4th ^ Γ ¹ ^ ',
ι . .,

10,600 28

281

278

930

12,500 35

267

288

926

Example 3?

The polyethylene of Example 1 was made at various percentages of a product of the formula

CH, \ ⁵ \ ³ . ,

CH ₅ -C- CH ₂ - C - C ₆ H ₄ - 0 - (CH ₂ - CH ₂ - O) ₉ -

CH- * mixed *

The results of the mechanical tests performed are in Table $ 1 listed »

301325/1006

Table III

Wt% additive ΕιυυΛ in the togetherness (ir. stun composition the) CJ CD 0 40 CO
OO 0.5 51 PO 1 62 ςη 2 90 ο 7, 119 O
cn 4th 133

Hardness notched

Preserved strength

kg / cm

Tensile fractures, elongation
Tensile stress%

10,600

28

281

278

930

11.200

250

298

947

ISJ

cn

U) O

Example 4

Some high density polyethylenes of various melt indexes (MFI) were mixed with 4% of a substance of the following * formula

C ₉ H ₁₉ - / £ jS - 0 - (CH ₂ - CH ₂ - O) ₈ - CH ₂ CH ₂ OH

The results of the ESCR tests are shown in Table IV.

density Tabel 17th MB ¹ I. g / cm ⁵ ESCR (hours) ESCR (hours) g / 10 ¹ 0.9577 (without additive) (4 % additive) 0.11 0.9568 22nd i 51 0.14 0.9628 51 300 0.26 0.9588 40 150 0.30 0.9581 39 183 0.80 0.9612 21 122 1.0 5 15th 46 example

ESCR determinations were made on polyethylene with a melt index of 0.8 (cf. Example 4, with and without additive, according to Example 4) by measuring the stress rupture in accordance with ASTM D-2552.
The results obtained are shown in Table V.

Table V

composition
% Additive

0 4th

ESCR (hours)

8.5 17

309825/1 006

Claims (6)

Claims 1. Polyethylene with improved resistance to cracking under tensile and impact stress, with a content of a small amount of an additive selected from the compounds of the general formula R - [- R ¹ O (R ² O) _n -J-X wherein R is a hydrocarbon chain which can consist of an alkyl, alkenyl or cycloalkyl radical; (R 0) a poly 2
is ether chain, in which R is an alkyl radical, unsubstituted or substituted by alkylene ", arylene, cycloalkylene, aralkylene groups and η is a number from 1 to 133; in which R can be a radical selected from the meanings given for R , in which case R and R is a single hydrocarbon group with a number of carbon atoms from 5 to, or in which R can be an aryl radical, the sum of the carbon atoms of R and R is between 5 and 30 and where A Ο R may also be selected from the radicals given for R, wherein the polyether chain grows in this case by one unit; wherein X is a group selected from -CHpCOOH, -CH ₂ CHO, -CH ₂ CN, -CH ₂ COOMe, -CH ₂ OH, -CH ₂ COOR ⁰ , wherein Me can be any monovalent metal and R is a hydrocarbon radical from the radicals listed above. 2. Polyethylene according to claim 1, characterized in that the amount of additive in the range from 3.1 to 13 wt .-%, based on the weight of the polymer. 3 · polyethylene according to one of the preceding claims, characterized characterized in that the additive has the formula C ₁₂ H ₂₅ - O - (CH ₂ CH ₂ - O) ₁₀ - CH ₂ COONa. 309825/1 0Ü6 4. Polyethylene according to one of claims 1 and 2, characterized in that the additive has the formula C ₉ H ₁₉ - / θ / - _{O - (CH 2} - CH ₂ - O) ₈ - CH ₂ - CH ₂ OH owns. 5 · polyethylene according to one of claims 1 and 2, characterized characterized in that the additive has the formula CH _x CH _x ■, CH _x - C - CH ₂ - C - Cjn - ( _{O - CH 2} - CH ₂ ) ₁₀ - OH CH _x CH _x owns. 6. Industrially manufactured objects and articles with improved tear and impact resistance, made from improved polyethylene according to claim 309825/1006